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Biomedical subjects

R M Schlobohm

Publications and source records attributed to R M Schlobohm.

13 recordsLinked to original sources
PubMed1990

Factors affecting perioperative pulmonary function in acute respiratory failure.

To determine the magnitude, duration, and associated factors of perioperative changes in pulmonary function, we retrospectively reviewed the medical records of 145 patients who required preoperative mechanical ventilation for acute respiratory failure before undergoing 200 surgical procedures. Patients were grouped into five pulmonary diagnostic categories: (1) adult respiratory distress syndrome (ARDS) (n = 49); (2) pneumonia (n = 20); (3) atelectasis (n = 65); (4) congestive heart failure (n = 11); and (5) acute ventilatory failure (n = 55). Sixty patients underwent intra-abdominal surgery, 135 patients required surgery on the periphery, and five patients had a thoracotomy. For all patients, PaO2/FIO2 declined significantly from 321 mm Hg (mean) preoperatively to 258 mm Hg intraoperatively, and shunt fraction (Qs/QT) increased from 0.16 to 0.23 without a significant change in PaCO2. The magnitude of the increase in Qs/QT did not differ among pulmonary diagnostic groups. Preoperatively, patients undergoing laparotomy had lower PaO2/FIO2 (278 vs 340) and higher Qs/QT (0.19 vs 0.14) than patients requiring surgery on the periphery. Intraoperatively, Qs/QT increased more during abdominal procedures than during peripheral procedures. Intraoperative hypoxemia (PaO2/FIO2 less than 80 mm Hg) occurred during 13 procedures. Hypoxemic patients had a mean increase in Qs/QT of 0.20 (0.25 preoperatively to 0.45 intraoperatively), and a significant increase in PaCO2 from 38 mm Hg to 45 mm Hg intraoperatively). In general, these patients had ARDS (n = 10), sepsis (n = 10), a laparotomy (n = 9), and intraoperative mechanical ventilation via the Ohio Anesthesia ventilator (n = 8), a commonly used operating room ventilator. Their preoperative peak airway pressure (54 cm H2O) and minute ventilation (20 L/min) requirements exceeded the capabilities of the Ohio Anesthesia ventilator and likely contributed to impaired gas exchange intraoperatively. Within the first several hours postoperatively, PaO2/FIO2 recovered to preoperative levels in all patients, even in those who had severe intraoperative hypoxemia develop and who underwent laparotomy. We conclude that most patients with acute respiratory failure receiving preoperative mechanical ventilation experienced mild-to-moderate deterioration in intraoperative pulmonary oxygen exchange that rapidly returned to preoperative levels after surgery. We recommend that necessary surgery not be postponed by concern that pulmonary function will be worsened by surgery and anesthesia.

Acute Disease↗
PubMed1977

Incidence and outcome of posttraumatic respiratory failure.

From 1972 through 1975, a total of 6,196 patients were admitted to San Francisco General Hospital Trauma Service, of whom 908 required admission to an intensive care unit and 390 required mechanical ventilation. Duration of mechanical ventilation was one week or less for 76%, two weeks or less for 90%, and four weeks or less for 97%. Survival in patients ventilated seven days or less was 64%, in patients ventilated 8 to 14 days it was 55%, and in patients ventilated 15 to 30 days it was 55%. The mortality for ventilated patients aged 20 to 49 years was 23% while for ventilated patients older than age 60 it was 53%. The average age of ventilated patients was 43. Use of controlled-pressure soft-cuff endotracheal tubes has eliminated tracheal-esophageal fistula and tracheal stenosis as causes of morbidity and mortality. Appropriate ventilator alarms have minimized fatalities due to mechanical equipment failure. Complications related to positive pressure ventilation, such as pneumothorax and subcutaneous emphysema, still occur in 12% to 18% of patients. In our patients who survived the acute respiratory distress syndrome, recovery of lung function was universal, and permanent disability was less than 1%.

Adolescent↗
PubMed1976

Ventilator-related extra-alveolar air in adults.

Extra-alveolar air (EAA) developed in 38 patients during mechanical ventilation. High ventilatory pressures and destructive lung disease predispose to EAA. Pneumoretroperitoneum and pneumoperitoneum are more common forms of ventilator-induced EAA in adults than generally realized; an associated pneumomediastinum was always identified when one of the two disorders above resulted from ventilation. Retroperitoneal air was located laterally along the liver and in the flanks, and changed little with change in patient position. Early detection of EAA may allow life-saving changes in therapy to be implemented.

Adolescent↗
PubMed1975

Control of respiratory therapy in flail chest.

Pulmonary mechanics and oxygenation were measured in 24 consecutive patients with posttraumatic flail chest requiring continuous mechanical ventilation. The mean duration of mechanical ventilation was fourteen days. Mortality was 38% for all patients, 29% if deaths from head injury are excluded. Pneumonia occurred in 4 patients (17%) and pneumothorax in 1 (4%). Vital capacity and maximal inspiratory force measurements were useful in assessing chest wall stabilization. Total lung compliance correlated negatively with fatal outcome from respiratory failure. The alveolar-arterial oxygen gradient was not useful in assessing chest wall stabilization.

Adult↗
PubMed1975

Shunt, lung volume and perfusion during short periods of ventilation with oxygen.

Twenty patients requiring ventilation for acute respiratory failure were studied to determine whether intrapulmonary shunt fraction (Qs/Qt) measured at an inspired oxygen concentration (FIO2) of 1.0 differs from Qs/Qt measured at the clinically indicated FIO2 and, if so, the mechanism by which this occurs. Qs/Qt increased from 15.5 +/- 1.8 per cent (mean +/- SE) at the clinically indicated inspired oxygen fraction (FIO2 0.3-0.6) to 21.7 +/- 2.1 per cent after 20 minutes at FIO2 1.0. Functional residual capacity (FRC) decreased by 6 +/- 6 per cent and total compliance (CT) by 10 +/- 6 per cent. Mean pulmonary arterial pressure fell from 21 +/- 2 to 17 +/- 2 mm Hg, whereas pulmonary capillary wedge pressure (PCWP) and cardiac output remained unchanged. Mixed venous oxygen tension increased from 37 +/- 1 to 45 +/- 2 mm Hg with 100 per cent oxygen. At 90 per cent oxygen, Qs/Qt increased from the value at low FIO2, but FRC and CT did not change. Simultaneous application of 100 per cent oxygen and a positive end-expiratory pressure (6 cm H2O) increased FRC, CT and Qs/Qt. Patients with increased PCWP showed smaller increases in Qs/Qt with 100 per cent oxygen. These findings suggest two mechanisms responsible for the increase in Qs/Qt: 1) redistribution of blood flow to nonventilated areas, resulting from the vasodilating effect of an increased oxygen tension in the vessels of hypoxic lung segments; 2) resorption atelectasis. Of the total change in Qs/Qt observed during ventilation with oxygen, 63 per cent was calculated to be due to factors other than a decrease in FRC. (Key words: Ventilation, positive end-expiratory pressure; Oxygen, pulmonary shunt and; Lung, compliance; Lung, shunts.)

Acute Disease↗
PubMedDate not supplied

Errors in data derived from pulmonary artery blood gas values.

Blood gas values were obtained from Swan-Ganz pulmonary artery catheters in 25 patients with acute pulmonary failure, with the objective of evaluating the possibility of contamination with "arterialized" blood and examining the mechanism by which this might happen. Blood oxygen content increased significantly from the main to a segmental pulmonary artery, proportional to the withdrawal rate of the sample. At 3 ml/min, distal contents ranged from 100 to 116% of proximal values (p less than 0.01). At 23 ml/min the range was 100-140% of proximal values (p less than 0.001). Sampling of blood from a Swan-Ganz catheter in the usual position for "wedge" pressure measurement, but with a balloon deflated, may lead to large errors in calculation of cardiac output by the Fick method and in calculation of intrapulmonary shunt fraction.

Blood Gas Analysis↗